The Magpies, which led through Alexander Isak’s sixth-minute penalty, trailed 3-1 with just 13 minutes remaining after Michail Anthony, Mohammed Kudus and Jarrod Bowen had struck in an incident-packed contest during which referee Rob Jones was at the centre of the action throughout.

However, a second Isak penalty reduced the deficit before Barnes levelled with seven minutes remaining to set up a grandstand finish during which he secured a 4-3 win with a stunning 90th-minute strike, before Anthony Gordon was sent off for a second bookable offence.

Eddie Howe’s men, whose injury problems deepened as they lost skipper Jamaal Lascelles, Tino Livramento and substitute Miguel Almiron, were rewarded for their resilience on a chaotic afternoon, but opposite number David Moyes, who was booked as tempers frayed, was scarcely able to believe what he had seen.

Newcastle could hardly have got off to a better start when it was awarded a penalty for Vladimir Coufal’s clumsy challenge on Gordon after the defender’s pass forward had been picked off by Fabian Schar and the former Everton frontman had carved his way into the area.

Jones pointed to the spot, but Isak had to await the outcome of a VAR check for offside against Gordon before sending keeper Alphonse Areola the wrong way from the spot.

Seconds after Lascelles’s premature departure, Michael Antonio fired a warning shot across Newcastle’s bows when he turned Dan Burn, who had been pushed into central defence as Livramento took over at left-back to accommodate substitute Emil Krafth on the right, but fired over with the Hammers looking the more threatening.

They duly forced their way back into the game with 21 minutes gone when Lucas Paqueta picked out Antonio’s run and he drew keeper Martin Dubravka before finishing emphatically.

Gordon fired straight at Areola after cutting inside from the left and then headed wide from Jacob Murphy’s teasing 36th-minute cross, but it was Bruno Guimaraes who went close deep into first-half stoppage-time when his curling attempt came back off the crossbar with Areola beaten.

However, the Hammers went ahead in the 10th minute of added time when, with Schar down, Paqueta was allowed to take a quick free-kick to Bowen, who fed Mohammed Kudus to fire past Dubravka amid furious protests from the home side.

Lukasz Fabianski replaced Areola before the restart and saw his side extend its advantage within three minutes when, after Thomas Soucek had got his head to Murphy’s corner, Kudus evaded Schar’s lunge and squared for Bowen to race from halfway and beat Dubravka despite Gordon’s valiant efforts to get back.

Fabianski easily claimed Guimaraes clipped shot and both Isak and Sean Longstaff stabbed horribly wide as the home side sought a way back into the game before the keeper denied Barnes.

However, Newcastle was awarded a second penalty after a VAR check on substitute Kalvin Phillips’s challenge on Gordon and Isak sent Fabianski the wrong way with an identical spot-kick to give his side hope with 13 minutes remaining.

It was level within six minutes when the Sweden international played Barnes through and he fired between Fabianski’s legs, and there was more to come in the final minute of normal time when Gordon, who was later dismissed after kicking the ball away, fed Barnes and he stepped inside before drilling an unstoppable shot beyond Fabianski’s despairing dive.